Roofing plate, installation and method therefor

ABSTRACT

A plate employed for securing substrate to a roofing structure employs a recessed central hub through which a fastener is driven. A barrier membrane covers the plate and is bonded in position to the plate. A sidewall of the recessed hub includes at least one vent opening to equalize pressure within the recessed hub during installation and post-installation.

BACKGROUND

This application relates generally to roofing plates which secure asubstrate to a decking structure by means of a fastener. Moreparticularly, this application relates to roofing plates which bond bymeans of an adhesive to an overlying barrier membrane.

In roofing installations to which the present application relates asubstrate is secured by a multiplicity of disc-like plates to a deckingstructure. The substrate is typically a thermal insulation layer such asa board of gypsum, resin foam or other insulating materials. The deckingstructure is typically a substructure of sheet steel, concrete or wood.Fasteners are driven through a central recessed hub of the plate tosecure the substrate.

For some applications, the plate has a heat activated adhesive on anupper surface of the plate. A barrier membrane, which is typically asingle ply waterproof membrane, is installed over the substrate and thegrid of metal plates. An induction tool, which generates magnetic eddycurrents in the metal plate, heats the metal plate and activates theadhesive. Upon cooling and setting, the adhesive then bonds theunderside of the membrane to the plate.

The membrane covers the plates prior to setting of the adhesive. Forsome conventional applications, there is a tendency for air to betrapped in the hub recess of the plate. The hub portion is sealed to thesubstrate at the bottom by the fastener head and at the top by themembrane. During the heating cycle, the trapped air expands. When theplate cools and the adhesive sets, a vacuum forms in the hub recess. Thevacuum may draw the membrane into the recess and form concave pockets orindentations across the top of the membrane surface. The consequence ofthe membrane indentations formed across the membrane surface is that thestretching of the membrane into the indentations results in stress onthe membrane, and the membrane may also tend to be susceptible tomoisture retention—ultimately jeopardizing the barrier bonding andintegrity of the membrane.

Related phenomena may also occur in other systems that employ variousforms of plates and fastening techniques. When a solvent based adhesiveis applied to the top of the plates, the solvent vaporizes and maypartially become trapped in the hub recess upon covering by themembrane. The trapped solvent may cause the membrane to essentially forma convex-like bubble. Such bubbles tend to cause peeling at theplate/membrane bonding interface and jeopardize the bond.

SUMMARY

A roofing plate comprises a central recessed portion which has a centralaxial opening. A raised portion surrounds the recessed portion. A wallwhich may be of a frustoconical form connects the raised portion and thecentral portion. A vent opening is formed in the wall. A peripheral rimsurrounds the raised portion. In one embodiment the recessed portionwall, raised portion and rim are generally symmetric about the axialopening. The plate is preferably metal. A heat activated adhesive may beapplied to the raised portion of the plate. The plate may be a one-pieceintegral member.

A method for installing a roofing system comprises driving a fastenerthrough a recessed portion of a roofing plate to secure a substrate suchas an insulation board to a decking structure. A membrane is placed overthe plate and substrate. The membrane is bonded to the substrate to forma cavity between the recessed portion and the membrane. The cavity isvented through a wall of the plate. A heat activated adhesive may beapplied to the plate prior to securing the plate into position.Alternatively, an adhesive may be applied to the plate after the plateis secured. A multiplicity of roofing plates are employed for securingthe substrate to the deck. The cavities formed in the plates are ventedduring the installation.

A roof installation comprises a decking structure. A substrate coversthe decking structure. A roofing plate has a fastener driven through thehub and into the structure to secure the substrate to the structure. Amember overlies the substrate and is bonded to the substrate byadhesive. A cavity is formed between the hub and the membrane. A ventpath through the plate communicates with the cavity. The plate may bemetal and the adhesive may be heat activated adhesive, pre-applied tothe plate. The vent path is located in a side wall of the recessed hub.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a roofing plate;

FIG. 2 is a sectional view of the roofing plate of FIG. 1 taken alongthe line 2-2 thereof;

FIG. 3 is a sectional view of a roof installation, showing a roofingplate, a fastener, a substrate, a decking structure and an overlyingbarrier membrane;

FIG. 4 is a perspective view of an installment stage of a roofinginstallation showing a plurality of roofing plates secured to asubstrate prior to covering by a roofing membrane; and

FIG. 5 is a sectional view of a prior art roof installation showing aprior art roofing plate, a fastener, a substrate, a decking structureand an overlying barrier membrane.

DETAILED DESCRIPTION

With reference to the drawings wherein like numerals represent likeparts throughout the several figures, a roofing plate is designatedgenerally by the numeral 10. The roofing plate 10 preferably has agenerally disc-like shape and a sturdy, reinforced construction. Theplate is secured to the decking structure 20 by a fastener 12 forretaining the substrate 22 in position to a deck substructure. For agiven installation, numerous plates are employed for the substrate andpositioned in a grid-like pattern. The substrate 22 is typically athermal insulation layer such as an insulation board. The deck structure20 may be a steel sheet or concrete. The roofing plate is configured toproperly engage the substrate and facilitate proper orientation of thefastener.

The roofing plate 10 has a central recessed hub 30 which defines thecentral opening 32 for the fastener. The bottom surface 34 of the hubprovides the plate engagement structure for the underside of the head 14of the fastener. The peripheral side 36 of the central hub tapersupwardly (preferably a frustoconical surface) to integrally join with anannular raised platform portion 40. The peripheral portion of the raisedplatform integrally tapers downwardly to form a circumferential rim 42which engages the substrate. Surface 34 and rim 42 are generallyparallel and have a spacing slightly offset from a co-planarrelationship. In some embodiments, the rim 42 is co-planar with thecentral surface 34 of the recessed hub. In the illustrated embodiment,the plate 10, rim 42, raised platform 40 and central hub 30 aregenerally axially symmetric about a central axis through the fasteneropening. The plate may be stamped from metal. Other plate shapes whichemploy a recessed hub are also possible.

A vent opening 50 is formed in the tapered recessed wall 36 of the hub.In one embodiment, for a plate having a platform diameter P of 80 mm or2.66 ins. and a hub surface diameters of 1.16 ins., the diameter of thevent opening 50 is 0.125 ins. and the opening is located at the midpointof the frustoconical side 36. The diameter H of the hub is 1.51 ins. andhas a depth D of approximately 0.17 ins. In some embodiments more thanone such opening may be formed. The opening 50 provides a vent passagewhich tends to equalize the pressure within the hub and surroundingregion during installation and post-installation and throughout theuseful life of the installation provided by the roofing plates.

Roofing plate 10 may be affixed with a heat activated adhesive 44 whichis applied to the raised platform 40 of the plate. In typical roofinstallations, numerous roofing plates are secured to the substrate viaa fastener which tightens against the recessed portion.

With reference to FIGS. 3 and 4, a barrier membrane 24 is then installedover the top of the roofing plates 10 and the substrate 20. The barriermembrane is typically a single-ply moisture resistant or waterproofsheet. The sheet is transported to the roofing structure in roll formand unrolled across the substrate.

An induction tool (not illustrated) on top of the membrane 24 is broughtinto the vicinity of the metal plates positioned under the membrane. Theinduction tool is energized so that magnetically induced eddy currentswithin the metal plate 10 heat the metal plate to thereby activate theadhesive 44. The adhesive, which is sandwiched between the membrane 24and the platform 40 of the plate, is ultimately cooled so that theadhesive sets and bonds the barrier membrane to the plates. In someembodiments, the adhesive may be mixed with metallic particles and theplate may not be metal.

Because in conventional installations, the barrier membrane essentiallyhermetically seals across the top of the hub and the bottom surface ofthe hub is sealingly engaged against the substrate, an air pocket may betypically formed in the hub. Under such conditions, when the prior artplate 11 cools, a seal forms between the underside of the fastener headand the top side of the plate adjacent the hole. A vacuum could becreated in the hub thereby forming a depression 27 such as illustratedin FIG. 5.

However, with reference to FIG. 3 and plate 10, because of the ventopening 50, the pressure will rapidly be equalized with the surroundingregion and consequently upon cooling and bonding of the plate, thepressure within the hub recess will not be sufficiently different toresult in creation of an indentation in the membrane. The membrane willessentially bond in a substantially planar, flat relationship 26 acrossthe entire expanse of the plate (which may-be slightly elevated abovethe substrate).

In an installation wherein the induction heat activated process is notemployed, the roofing plates are secured against the substrate in agrid-like pattern to anchor the substrate to the decking structure.Solvent based adhesive is then sprayed or otherwise applied across thetops of plates. The barrier membrane is then laid or rolled over thesubstrate and plates. Any solvent which typically vaporizes off from theadhesive which may become trapped in the recessed hub will be vented viathe vent opening 50 to essentially equalize the local pressure andprevent any bubbling effect across the membrane.

While preferred embodiments of the foregoing have been set forth forpurposes of description, the foregoing should not be deemed alimitation. Accordingly, various modifications, adaptations oralternatives may occur to one skilled in the art without departing fromthe spirit and the scope of the appended claims.

1. A roofing plate comprising: a central recessed portion defining acentral axial opening; a raised portion surrounding said recessedportion; a wall connecting said raised portion and central portion anddefining a vent opening; and a peripheral rim surrounding said raisedportion.
 2. The roofing plate of claim 1 wherein said recessed portion,said wall, said raised portion and said rim are generally symmetricabout said axial opening.
 3. The roofing plate of claim 1 wherein saidplate is metal.
 4. The roofing plate of claim 3 further comprising aheat activated adhesive applied to said raised portion.
 5. The roofingplate of claim 1 wherein said plate is a one piece integral member.
 6. Amethod for installing a roofing system comprising: (a) driving afastener through a recessed portion of a roofing plate to secure asubstrate to a decking structure; (b) placing a membrane over said plateand substrate; (c) bonding said membrane to said substrate to form acavity between said recessed portion and said membrane; and (d) ventingsaid cavity through a wall of said plate.
 7. The method of claim 6wherein step 1 (c) further comprises applying an adhesive to said plate.8. The method of claim 6 wherein step (c) further comprises heating aheat activated adhesive applied to the plate.
 9. The method of claim 6wherein step (a) further comprises driving a fastener through a recessedportion of a roofing plate for a multiplicity of roofing plates, andsteps (c) and (d) further comprise forming a cavity for each said plateand venting each said cavity.
 10. A roof installation comprising: adecking structure; a substrate covering said decking structure; aroofing plate having a recessed hub with a fastener driven through saidhub and into said structure to secure said substrate to said structure;a membrane overlying said substrate and bonded to said substrate byadhesive and forming a cavity between said recessed hub and saidmembrane; and a vent path communicating through said plate with saidcavity.
 11. The roof installation of claim 10 wherein said adhesive isheat activated adhesive applied to said plate.
 12. The roof installationof claim 10 wherein said plate is metal.
 13. The roof installation ofclaim 10 further comprising a multiplicity of roofing plates andfasteners each of which form a cavity and a vent path communicatingthrough said plate with said cavity.
 14. The roof installation of claim10 wherein said vent path is located in a sidewall of said recessed hub.